Intraocular lens

ABSTRACT

An intraocular lens comprises an optic and at least two haptics. Each haptic is offset in an anterior direction from a central optic plane of the optic. The offset allows for predictable posterior vaulting upon implantation.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 12/954,424, filed Nov.24, 2010, which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to an intraocular lens and, moreparticularly, to an intraocular lens configured for implantation byminimally invasive surgery.

BACKGROUND

After implantation of an intraocular lens in the eye, epithelial cellsmay migrate from the haptic to the refractive region of the lens andthereby obscure the lens. This condition is known as posterior capsularopacification (PCO). Also, the refractive region of an intraocular lensmay vault or push forwardly (i.e., anteriorly) in the eye when thehaptic is radially compressed, such as may occur as the haptic is beingseated within the capsular bag of the eye and/or when an external forceis applied to the eye after implantation. Upon implantation, predictableposterior vaulting allows the final position of the lens to be morepredictable thus leading to a better prediction of emmetropia. There isa continuing need to prevent PCO and make the final position of the lensmore predictable.

SUMMARY OF THE INVENTION

Briefly and in general terms, the present invention is directed to anintraocular lens. In aspects of the present invention, an intraocularlens comprises an optic being substantially circular and having an opticanterior surface, an optic posterior surface, and an optic edge surfaceat a periphery of the optic, the optic edge surface connecting the opticanterior surface and the optic posterior surface, and at least twohaptics, each haptic having a shoulder segment coupled to the peripheryof the optic, an arm segment extending out from the shoulder segment, ahaptic anterior surface, and a haptic posterior surface, wherein acentral optic plane divides the optic edge surface into an anterioroptic edge surface and a posterior optic edge surface that issubstantially equal in area to the anterior optic edge surface, whereina central optic plane divides the optic edge surface in half, wherein acentral haptic plane divides the arm segment in half, and the centralhaptic plane is spaced apart in an anterior direction from the centraloptic plane.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a posterior plan view of an intraocular lens according to anembodiment of the present invention, showing an optic and two hapticshaving a step feature that prevents epithelial cell migration to theoptic.

FIG. 2 is a side view of the intraocular lens of FIG. 1, showing acentral optic plane passing through an arm, segment of the haptics.

FIG. 3 is a perspective view of the intraocular lens of FIG. 1.

FIG. 4 is an anterior plan view of an intraocular lens according toanother embodiment of the present invention.

FIG. 5 is a side view of the intraocular lens of FIG. 4, showing acentral optic plane located posterior to an arm segment of the haptics.

FIG. 6 is a perspective view of the intraocular lens of FIG. 4.

FIG. 7 is a detail side view showing the optic-haptic junction of theintraocular lens of FIG. 1.

FIG. 8 is a detail side view showing the optic-haptic junction of theintraocular lens of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is understood that with regard to this description and the appendedclaims, any reference to any aspect of this invention made in thesingular includes the plural and vice versa unless it is expresslystated or unambiguously clear from the context that such is notintended. Thus, reference to “a” haptic or “the” haptic refers to notonly one haptic but to two or more haptics unless is it unambiguouslystated or unambiguously obvious from the context that such is notintended.

As used herein, any term of approximation such as, without limitation,near, about, approximately, substantially, essentially and the like meanthat the word or phrase modified by the term of approximation need notbe exactly that which is written but may vary from that writtendescription to some extent. The extent to which the description may varywill depend on how great a change can be instituted and have one ofordinary skill in the art recognize the modified version as still havingthe properties, characteristics and capabilities of the modified word orphrase. For example without limitation, something that is described as“substantially circular” in shape refers to a shape that is perfectlycircular and a shape that one skilled in the art would readily recognizeas being circular even though diameters measured at multiple locationson the circle are not exactly the same. As another non-limiting example,a first structure that is described as “substantially parallel” inreference to a second structure encompasses an orientation that isperfectly parallel and an orientation that one skilled in the art wouldreadily recognize as being parallel even though distances betweencorresponding locations on the two respective structures are not exactlythe same. In general, but with the preceding discussion in mind, anumerical value herein that is modified by a word of approximation mayvary from the stated value by ±15%, unless expressly stated otherwise.

As used herein, the terms “preferred,” “preferably,” and the like referto preferences as they existed at the time of filing this patentapplication.

As used herein, an intraocular lens or IOL refers to a light-bendinglens that is surgically placed within the eye as a replacement for thenatural lens of the eye (pseudophakic lens) or as an adjunct to theimage focusing property the natural lens (phakic lens), in either casefor the purpose of improving the vision of—or in some cases returningvision to—a patient in whose eye the IOL is implanted.

As used herein the terms “anterior” and “posterior” refer to the spatialrelationship of the construct once it is implanted in the eye. Thus, ananterior surface of an IOL faces the external environment. A posteriorsurface of an IOL faces the retina.

As used herein, a “leading edge” of a construct, such as a haptic,refers to the edge with the larger radius of curvature while,conversely, a “trailing edge” refers to the edge with the smaller radiusof curvature.

As used herein, a “refractive region” of an IOL herein refers to thatportion of the lens that performs the function of focusing or assistingin focusing an image on the retina of the eye.

As used herein, a “haptic” refers to one or more extensions extendingoutward from the coupling region where they act as struts to support theIOL in the capsular bag. The coupling region refers to an annularsegment region at the periphery of the refractive region. Haptics areknown with many different designs such as, without limitation, singlepiece, multi-piece, plate, closed loop and open loop. For the purposesof this invention a haptic comprises a single piece open-loop design.

As used herein, a “through hole” refers to a lumen that extends from onesurface of a structure completely through the structure to anothersurface of the structure such that, if desired, a fluid could passcompletely through the structure.

As used herein, an “exterior angle” between two constructs refers to anangle outside of the two constructs, such angle capable of beingmeasured along an arc that runs external to the two constructs, from oneconstruct to the other.

As used herein, a “barrier angle” refers to an exterior angle between aposterior arm surface of a haptic and a step surface intersecting theposterior arm surface, the angle being sufficient to prevent epithelialcells from migrating past the step surface.

As used herein, an “optical axis” refers to an imaginary straight linepassing through the geometric center of the refractive region of an IOLand joining the two centers of curvature of the anterior and posteriorsurfaces of the refractive region.

Referring now in more detail to the exemplary drawings for purposes ofillustrating embodiments of the invention, wherein like referencenumerals designate corresponding elements among the several views, thereis shown in FIGS. 1-6 an intraocular lens 10. Intraocular lens 10 ispreferably made of an elastic polymer that allows it to be folded forcapsular bag implantation by minimally invasive surgical methods and tounfold, either autonomously or through further manipulation, onceimplanted. Intraocular lens 10 comprises optic 12 that is substantiallycircular and serves as the refractive region of the lens. Optic 12comprises optic anterior surface 14, optic posterior surface 16, andoptic edge surface 18 at periphery 20 of the optic. Optic anteriorsurface 14 can have a spherical radius and optic posterior surface 16can have an aspheric radius. The optic anterior and posterior surfacesmay also be defined as either spherical, aspheric, toric, or a customprofile to correct inherent corneal aberrations, or a combination of theabove. Optical axis 17 (FIGS. 2 and 5) passes through the centers ofcurvature of anterior surface 14 and optic posterior surface 16. Opticedge surface 18 connects optic anterior surface 14 and optic posteriorsurface 16. Optic edge surface 18 can have a rough texture to minimizeglare.

Intraocular lens 10 further comprises at least two haptics 22. Eachhaptic 22 has shoulder segment 24 coupled to optic periphery 20, and armsegment 26 extending out from shoulder segment 24. Each haptic 22terminates at free end 27 of arm segment 26. Haptics 22 are of an openC-loop design although other open loop designs can be accommodated andare within the scope of this invention. Each haptic 22 also has hapticanterior surface 28 and haptic posterior surface 30 on opposite sides ofshoulder segment 24 and arm segment 26. It is understood that haptics 22of this embodiment are presently preferred to be symmetrical so that anydimension and any feature shown for one haptic is the same for the otherhaptic even though it may not be expressly shown as such in the figures.It is, however, within the scope of the present invention for haptics tobe asymmetrical so that a dimension or feature for one haptic is absentfrom the other haptic or is not the same as a corresponding feature ordimension for the other haptic.

Haptic posterior surface 30 comprises step feature 32 at shouldersegment 24. After implantation in a patient's eye, epithelial cells mayattach to arm segment 26, but step feature 32 provides a barrier toprevent the cells from migrating onto the refractive region of the lens.In FIGS. 1 and 2, the epithelial cells are illustrated as small sphereson the posterior side of arm segments 26.

In a presently preferred embodiment, step feature 32 is a geometricdiscontinuity, such as a ledge, ridge or a bump, that is spaced apartfrom optic periphery 20. Step feature 32 extends continuously acrossshoulder segment 24 from leading edge 36 to trailing edge 38.

As shown in FIGS. 2 and 5, haptic posterior surface 30 comprisesposterior arm surface 42 extending across arm segment 26. Step feature32 protrudes in the posterior direction 34 from posterior arm surface42, so as to form a barrier in the form of step surface 44. Step surface44 intersects posterior arm surface 42 at a barrier angle A greater thanzero. Barrier angle A can be from about 5 degrees to about 175 degrees,from about 5 degrees to about 90 degrees, or from about 90 degrees toabout 175 degrees. In a presently preferred embodiments, barrier angle Ais from about 80 degrees to about 110 degrees, and more narrowly atabout 90 degrees. Having barrier angle A at less than 90 degrees resultsin an undercut, wherein step surface 44 is tilted to a position above aportion of posterior arm surface 42. In FIG. 2, barrier angle A is about135 degrees. In FIG. 5, barrier angle A is substantially 90 degrees sothat step surface 44 is substantially perpendicular to posterior armsurface 42.

Step feature 32 causes various parts of haptic posterior surface 30 tobe uneven in elevation. Haptic posterior surface 30 includes posteriorshoulder surface 46 that extends across shoulder segment 24. As shown inFIG. 2, posterior shoulder surface 46 is substantially planar and isuneven with the remainder of haptic posterior surface 30.

In the embodiment of FIGS. 4-6, posterior shoulder surface 46 andposterior arm surface 42 are substantially planar, are substantiallyparallel to each other, and are spaced apart from each other by adistance from 0.05 mm to 0.50 mm along an imaginary straight line 43that is parallel to the optical axis 17. More narrowly, the distance isabout 0.10 mm. The distance is the height of step feature 32 and isselected to prevent migration of epithelial cells to the refractiveregion of the lens.

Intraocular lens 10 may have, in combination with the step feature 32,features which addresses vaulting as described below.

In the embodiment of FIGS. 4-6, posterior shoulder surface 46 andposterior arm surface 42 are located on opposite sides of central opticplane 52 which is disposed centrally between curved anterior edge 54 ofoptic edge surface 18 and curved posterior edge 56 of optic edge surface18. Central optic plane 52 passes through shoulder segment 24. Theentire arm segment 26 is anterior to central optic plane 52, so centraloptic plane 52 does not pass through arm segment 26. Having arm segments26 located anterior to central optic plane 52 causes arm segments 26 tobend in an anterior direction as shown by arrows 55 (FIG. 5) when radialcompressive forces 57 (FIGS. 4 and 5) are applied to arm segments 26.The anterior (or forward) bend of arm segments 26 biases or tends topush optic 12 in the opposite direction, in the posterior (or rearward)direction 34, which prevents or minimizes anterior vaulting of optic 12.

In the embodiment of FIGS. 1 and 2, the entire arm segment 26 is notanterior to the central optic plane 52. Central optic plane 52 passesthrough arm segment 26 and shoulder segment 24. Each haptic 22 hashaptic edge surface 58 connecting haptic anterior surface 28 and hapticposterior surface 30. As shown in FIG. 2, central haptic plane 60 isdisposed centrally within arm segment 26 and between curved anterioredge 62 of haptic edge surface 58 and curved posterior edge 64 of hapticedge surface 58. Central haptic plane 60 is offset in an anteriordirection 66 from central optic plane 52. Having central haptic plane 60located anterior to central optic plane 52 causes the optic 12 to shiftin the posterior direction when radial compressive forces 57 (FIGS. 1and 2) are applied to arm segments 26 after implantation.

In a presently preferred embodiment, central optic plane 52 is centeredbetween anterior edge 54 of optic edge surface 18 and posterior edge 56of optic edge surface 18. Broken line 53 (FIG. 3) on optic edge surface18 indicates where central optic plane 52 intersects optic edge surface18. Central haptic plane 60 is centered between anterior arm surface 72and posterior arm surface 42. Broken line 61 (FIG. 3) on haptic edgesurface 58 indicates where central haptic plane 60 intersects hapticedge surface 58. Central optic plane 52 intersects haptic edge surface58 below broken line 61. Central haptic plane 60 is substantiallyparallel to central optic plane 52 and is spaced apart in the anteriordirection 66 from central optic plane 52 and are spaced apart from eachother by plane-to-plane offset distance 73.

In some embodiments, as shown in FIG. 3, central optic plane 52 dividesoptic edge surface 18 in two halves, as anterior optic edge surface 74and posterior optic edge surface 75 substantially equal in area toanterior optic edge surface 74. Central haptic plane 60 divides armsegment 26 in two halves, as anterior arm volume 76 and posterior armvolume 78 substantially equal in volume to anterior arm volume 76.

In some embodiments, for multiple points on central optic plane 52, eachpoint is substantially equidistant from anterior edge 54 and posterioredge 56. For multiple points on central haptic plane 60, each point issubstantially equidistant from anterior arm surface 72 and posterior armsurface 42.

FIG. 7 is a partial detailed view of FIG. 2. As shown in FIG. 7,anterior arm surface 72 is located entirely anterior to central opticplane 52 while posterior arm surface 42 is located entirely posterior tocentral optic plane 52. FIG. 8 is a partial detailed view of FIG. 5. Asshown in FIG. 8, both anterior arm surface 72 and posterior arm surface42 are located entirely anterior to central optic plane 52. In bothFIGS. 7 and 8, anterior arm surface 72 is spaced apart from centraloptic plane 52 by first offset distance 80 as measured on a linesubstantially parallel to optical axis 17 (FIGS. 2 and 4). Posterior armsurface 42 is spaced apart from central optic plane 52 by second offsetdistance 82 on a line substantially parallel to optical axis 17. Secondoffset distance 82 is less than first offset distance 80, which causesarm segment 26 to bend in an anterior direction when radial compressiveforces are applied to arm segment 26. This bending, in turn, causespredictable posterior displacement of optic 12 when implanted in thecapsular bag of the eye.

Intraocular lens 10 may have, in combination with step feature 32 andvaulting features, another feature which facilitates bending of thehaptic 22 at shoulder segment 24, such as shown in the embodiment ofFIGS. 1-3 and 7 and the embodiment of FIGS. 4-6 and 8. Haptic anteriorsurface 28 comprises taper surface 68 that extends across the shouldersegment 24. The shoulder segment 24 has through hole 70 that runs fromhaptic posterior surface 30 to taper surface 68. Through hole 70 allowshaptic 22 to bend at shoulder segment 24 when radial compressive forces57 are present, without resulting in astigmatic distortions on optic 12.Through hole 70 may be circular in cross-section as illustrated, or itmay have virtually any geometrical shape such as elliptical, square,rhomboid, quadrilateral, regular or irregular polygonal or simplyirregularly shaped. Posterior shoulder surface 46 extends acrossshoulder segment 24 and connects optic periphery 20 and step feature 32.Posterior shoulder surface 46 is opposite taper surface 68, so throughhole 70 extends from posterior shoulder surface 46 to taper surface 68.

As shown in FIG. 4, taper surface 68 has cross dimension 69 that narrowswith increasing radial distance from optic periphery 20. Cross dimension69 is at a maximum at optic periphery 20. The taper surface 68intersects and ends at anterior arm surface 72. Cross dimension 69 is ata minimum where taper surface 68 intersects anterior arm surface 72.Taper surface 68 is uneven with anterior arm surface 72 in such a waythat thickness 71 (FIG. 7) of shoulder segment 24 is at a minimum atoptic periphery 20 and is at a maximum where taper surface 68 intersectsanterior arm surface 72. The decrease in thickness 71 of haptic 22toward optic periphery 20 facilitates anterior bending of haptic 22along arrow 55.

The surfaces and edges of intraocular lens 10 are defined by variousdimensional parameters, such as diameters (D), radii (R), lengths (L),and thicknesses (T). Dimensional parameters are labeled in FIGS. 4 and 5with a letter followed by a number. For example, D1 and D2 refer to afirst diameter and a second diameter. Diameters D1 through D3 have acommon center point, C, at the center of optic 12. R1 and R2 refer to afirst radius and a second radius. Each radius, R, is centered ormeasured out from a corresponding point, P, located according toorthogonal X-, Y- and Z-axes centered at center point C. The Z-axiscorresponds to optical axis 17 of optic 12. For example, R1 and R2 referto radii centered or measured out from points P1 and P2. Diameter D4 forthrough hole 70 is centered at point P6. The approximate location ofeach point, P, is indicated by the symbol “+” in FIGS. 4 and 5.

In a presently preferred embodiment, values for the dimensionalparameters (D, R, L and T) and locations for various points (P) are asshown in TABLES 1 and 2, although other values can be accommodated andare within the scope of this invention. The locations or coordinates forvarious points (P) are measured from center point C. The haptics on theintraocular lens 10 is rotationally symmetric about the Z-axis passingthrough center point C. Dimensional parameters and point locations givenfor one haptic 22 apply accordingly to the opposite haptic 22. Thedegree of rotational symmetry is 180 degrees, such that the two haptics22 trade positions upon rotation of 180 degrees.

TABLE 1 Preferred Dimension Parameter Range (mm) Ideal Dimension (mm) D14.50 to 7.50 6.00 D2 D1+ (0 to 0.40) D1+ 0.20 D3 D1+ (0 to 2.00) D1+1.00 D4 0.10 to 0.50 0.37 L1 10.00 to 14.00 12.50  R1 4.00 to 4.40 4.23R2 0.15 to 0.25 0.19 R3 0.70 to 0.75 0.74 R4 3.50 to 3.75 3.62 R5 0.30to 0.35 0.33 R6 0.50 to 1.00 0.75 T1 0.10 to 0.50 0.45 T2   0 to 0.400.10 T3 0.10 to 0.50 0.20

TABLE 2 Point X Coordinate (mm) Y Coordinate (mm) Z Coordinate (mm) P1−1.524 1.524 — P1 −2.575 5.480 — P3 −2.158 5.833 — P4 1.524 −1.524 — P51.161 3.205 — P6 −2.052 −2.647 — P7 — 2.211 −1.782

As shown in FIG. 4, the size of optic 12 in plan view is defined bydiameters D1 and D2. Most of optic periphery 20 coincides with D1. Nearthe optic-haptic junction, optic anterior surface 18 extends beyonddiameter D1 to diameter D2. At the haptic-optic junction, diameter D2defines optic periphery 20, which marks the start of taper surface 68.As shown in FIG. 5, taper surface 68 is concave and is defined in partby inside radius R6. Taper surface 68 is bounded in plan view bydiameters D2 and D3. Taper surface 68 intersects anterior optic surface14 at diameter D2 and intersects anterior arm surface 72 at diameter D3.Thickness T1 corresponds to the Z-axis height of the portion of hapticedge surface 58 at arm segment 26. T1 also corresponds to the Z-axisseparation between anterior edge 62 of haptic edge surface 58 andposterior edge 64 of haptic edge surface 58. Thickness T2 corresponds tothe Z-axis height of step surface 44. T2 also corresponds to the Z-axisseparation between posterior arm surface 42 and posterior shouldersurface 46. Thickness T3 corresponds to the Z-axis height of optic edgesurface 18. T3 also corresponds to the Z-axis separation betweenanterior edge 54 of optic edge surface 18 and posterior edge 56 of opticedge surface 18.

While several particular forms of the invention have been illustratedand described, it will also be apparent that various modifications canbe made without departing from the scope of the invention. It is alsocontemplated that various combinations or subcombinations of thespecific features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the invention. Accordingly, it is not intended that theinvention be limited, except as by the appended claims.

1. An intraocular lens, comprising: an optic being substantiallycircular and having an optic anterior surface, an optic posteriorsurface, and an optic edge surface at a periphery of the optic, theoptic edge surface connecting the optic anterior surface and the opticposterior surface; and at least two haptics, each haptic having ashoulder segment coupled to the periphery of the optic, an arm segmentextending out from the shoulder segment, a haptic anterior surface, anda haptic posterior surface; wherein a central optic plane divides theoptic edge surface in half, wherein a central haptic plane divides thearm segment in half, and the central haptic plane is spaced apart in ananterior direction from the central optic plane.
 2. The intraocular lensof claim 1, wherein the haptic anterior surface of each haptic comprisesan anterior arm surface, the haptic posterior surface of each hapticcomprises a posterior arm surface, the anterior arm surface of eachhaptic is spaced apart from the central optic plane by a first offsetdistance on a line parallel to an optical axis of the optic, theposterior arm surface of each haptic is spaced apart from the centraloptic plane by a second offset distance on the line parallel to theoptical axis, and the second offset distance is less than the firstoffset distance.
 3. The intraocular lens of claim 2, wherein theanterior arm surface of each haptic and the posterior arm surface ofeach haptic are located anterior to the central optic plane.
 4. Theintraocular lens of claim 2, wherein the anterior arm surface of eachhaptic is located anterior to the central optic plane, and the posteriorarm surface of each haptic is located posterior to the central opticplane.
 5. The intraocular lens of claim 2, wherein the haptic anteriorsurface of each haptic comprises a taper surface extending across theshoulder segment, the taper surface is concave and intersects theanterior arm surface.
 6. The intraocular lens of claim 5, wherein theshoulder segment of each haptic has a through hole from the hapticposterior surface to the taper surface of the haptic anterior surface.7. The intraocular lens of claim 1, wherein the haptic posterior surfaceof each haptic comprises a step feature at the shoulder segment.
 8. Theintraocular lens of claim 7, wherein the haptic posterior surface ofeach haptic comprises a posterior arm surface, and the step feature ofeach haptic protrudes in a posterior direction from the posterior armsurface.
 9. The intraocular lens of claim 8, wherein the step feature ofeach haptic comprises a step surface that intersects the posterior armsurface at a barrier angle substantially greater than zero.
 10. Theintraocular lens of claim 9, wherein the haptic anterior surface of eachhaptic comprises an anterior arm surface spaced apart from central opticplane by a first offset distance on a line parallel to an optical axisof the optic, the posterior arm surface of each haptic is spaced apartfrom the central optic plane by a second offset on the line parallel tothe optical axis, and the second offset is less than the first offsetdistance.